Submitted to: PLoS One
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/25/2010
Publication Date: 12/9/2010
Citation: Dewaard, J.R., Mitchell, A., Keena, M.A., Gopurenko, D., Boyken, L.M., Armstrong, K.F., Pogue, M.G., Lima, J., Floyd, R., Hanner, R., Humble, L.M. 2010. Toward a global barcode library for Lymantria (Lepidoptera: Lymantriinae) tussock moths of biosecurity concern. PLoS One. 5(12):1-10. Interpretive Summary: Gypsy moths are some of the most destructive forest pests in the world and cause millions of dollars damage annually worldwide. Potential invasive species of gypsy moths from temperate and sub-tropical Asia are a threat to the forests of North America, Australia, and New Zealand. This paper describes a method using molecular diagnostic tools, including DNA barcoding, to assist in identifying species and geographic sources of populations. This study uses 36 species of gypsy moths from 35 countries to develop a barcode reference library to be used to help in the identification of invasive species of gypsy moths. The results will be useful for molecular scientists, entomologists, and Forest Service personnel from North America, Australia, and New Zealand.
Technical Abstract: Detecting and controlling the movements of invasive species, such as insect pests, relies upon rapid and accurate species identification in order to initiate containment procedures by the appropriate authorities. Gypsy moth Lymantria dispar L., introduced from Europe in the 19th century, has become a significant forestry pest in eastern North America. In recent years, incursions of gypsy moth and other Lymantria species have been detected and prevented from establishing in western North America and in several countries. Consequently this genus has been a focus for the development of molecular diagnostic tools, including DNA barcoding, to assist in identifying species and source populations. In this study we expand the taxonomic and geographic coverage of the DNA barcode reference library, and further test the utility of this diagnostic method, both for species/subspecies assignment and for determination of geographic provenance of populations. COI barcodes were obtained from 518 individuals and 36 species of Lymantria, originating from 35 countries, including sequences assembled from previous studies, and new sequences generated from vouchered material in public collections, as well as from intercepted specimens obtained from surveillance programs in Canada. A maximum likelihood tree was constructed, revealing high bootstrap support for the majority of species clusters. Species assignment using a Bayesian statistical algorithm was also tested, and resulted in correct assignment to species and subspecies in all instances. The performance of barcoding was also compared against the commonly employed NB restriction digest system (also based on COI); while the latter was found to be informative for discriminating a limited set of species, COI barcode sequences provide greater resolution and generality by encompassing a greater number of haplotypes across all species, none shared between species. This study demonstrates the efficacy of DNA barcodes for diagnosing species of Lymantria and reinforces the view that the approach is an untapped resource with substantial potential for use in biosecurity and surveillance. Biomonitoring agencies currently employing the NB restriction digest system would gather more information by transitioning to the use of DNA barcoding, a change which could be made relatively seamlessly as the same gene region underlies both protocols.